Explore topic-wise InterviewSolutions in Current Affairs.

Calcium is responsible for blood clotting

(b) Calcium ions and platelet factors

Hypertension

(a) Right auricle and right ventricle

Erythroblastosis foetalis

All animals depend on plants (directly or indirectly) for their food needs. They are hence called consumers and also heterotrops. If they feed on the producers, the plants, they are called primary consumers, and if the animals eat other animals which in turn eat the plants (or their produce) they are called secondary consumers likewise, you could have tertiary consumers too. Obviously the primary consumers will be herbivores. Some common herbivores are insects, birds and mammals in terrestrial ecosystem and molluses in aquatic ecosystem. The consumers that feed on these herbivoes are carivores, or more correctly primary carnivores (though secondary consumers). Those animals that depend on the primary carrivores for food are labelled secondary carnivores. A simple graging food chair (GFC) is depicted below:

Grass.................Goat............................Man

(producer)  (primary Consumer)  (Secondary consumer)

The detritus food chain (DFC) begins with the dead organic matter. It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria. They meet their energy and nutrient requirements by degrading dead organic matter or detritus these are also known as saprophytes.

In an aquatic ecosystem, GFC is the major conduct for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flowers through the detritus food chair through the GFC. Detritus food chair may be connected with the grazing food chair at some levels. These natural interconnection of food chains make it a food web.

Difference between messenger RNA and transfer RNA is following:– 

(i) Messenger RNA – It carries the information regarding the definite sequence of amino acids in a polypeptide chain. It carries the instruction coded in DNA to the cytoplasm and finally determines the amino acids sequence in the synthesis of polypeptide chain. 

(ii) Transfer RNA – Each form carries a specific amino acids from the amino acid pool to the mRNA on the ribosome to form a polypeptide. 

(iii) Ribosomal RNA – Ribosomal RNA takes part in the structure and physiology of ribosome.

Some time, hereditary and unknown factors attack on the selfcells of the body due to which it causes harmful effects and produces autoimmune diseases like rhumatoid arthritis.  

The overall ability of the host to fight the disease causing organism conferred by the immuni system is called immunity.

Immunity is of two types:

(i) Innate immunity

(ii) Acquired immunity.

Innate immunity:

Innate immunity is non-specific type of defence, that is present at the time of birth. Innate immunity consists of four types of barriers.

(i) Physical barriers: Skin on our body is the main farrier which prevents entry of the micro-organisms.

(ii) Physiologyical barriers: Acid in the stomach, saliva in the mouth, tears from eyes, all prevent microbial growth.

(iii) Cellular barriers: Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL - neutrophills) and monocytes and natural killer (types of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes.

(iv) Cytokine barriers: Virus infected cells secrete protein called interferenos which protect non-infected cells from further viral infection.

Ecosystem – A system formed by inter-relationship of all living organism and environment in a specific area is called ecosystem. 

Kinds of ecosystem:– 

(a) Terresterial ecosystem 

(b) Aquatic ecosystem 

(c) Artificial eosystem 

In the course of giving theory of evolution, the “Natural selection” given by Darwin means that Nature not always be same, it changes continuously and therefore it selects adaptable organism and short out non-adaptable. This fact is called natural selection of Darwin. 

The mechanism of sex determination has always been a puggle before the genetists.

Henking (1891) could trace a specific nuclear structure all through spermatogenesis in a few insects and it was also observed by him that 50 percent of the sperm received this structure after spermatogenesis, whereas the other 50 percent could not receive this Henking gave a name to this structure as the X-body but he could not explain its sisgnificance Further investigations by other scientists led to the conclusion that the 'X body' of Henking was in fact a chromosome and that is why it was given-the name X-chromosome. It was also observed that in a large number of insects the mechanism of sex determination is of the XO type i.e. all eggs bear an additional X-chromosome besides the other chromosome (outsomes) On the other hand, some of the sperms bear the X-chromosome whereas some donot. Eggs fertilised by X-chiomosome becomes females and that fertilised by sperms that do not have an X-chromosome become males. Crassh copper is an example of XO type of sex determination. ln a large number of insects and mammals including man, XY type of sex determination is seen where both male and female have same number of chromosomes.

Among the males an X-chromosome is present whereas its counterpart is distinetly smaller and are called the Y-chromosome females however have a pair of X chromosome. Hence the males have outosomes plus XY and females have outosomes plus XX.

Calcium phosphate, calcium carbonate, magnesium phosphate

Endoparasatic protozoans:

The protozoans which reside inside the body of organisms are known as endoparasitic protozoans E.g., each in our stomach ovule.

The salient features of the double-helix.

Structure of DNA are as following:

(i) It is made of two polynucleotide chains, where the backbone is constituted by sugar-phosphate and the bases project inside.

(ii) The two chains have anti-parallel polarity. It means, if one chain has the polarity 5'-3', the other has 3'-5'.

(iii) The bases in two strands are paired through hydrogen bond (H-bonds) forming base pairs. Adenine forms two hydrogen bonds with thymine from opposite strand and vice-versa. Similarly, Guanine is bonded with cytosine with three H-bonds.

(iv) The two chains are coiled in a right handed fashion.

(v) The plane of one base pair stacks over the other in double helix.

Sugical methods of contraception are called sterilisation. Surgical intervention blocks gamete transport and thereby prevent conception. Sterilisation procedure in the male is called vasectomy and that in the female is called tubectomy.

Corpus luteum is formed from the ruptured graphian follicle. (i) It secretes progesteron hormone during the luteal phase of the menstrual cycle. (ii) It also allows the endometrium of the uterus to proliferate and to prepare itself for implantation. 

Antibiotics – It is a chemical substance which is prepared from fungi and bacteria. Antibiotics are used to prevent the growth of bacteria or kill the bacteria. Antibiotics prepared from biotechnology are– 

(i) Penicillin 

(ii) Erythromycin 

(iii) Cephalosporin 

(iv) Neomycin

The increase in global temperature due to CO₂ concentration is called global warming.

The effects of global warming are:

(a) Crop losses

(b) Deterioration of building

(c) Respiratory disorder

Steps to overcome it:

Electrostatic precipitators can reduce smoke and dust from industnies.

Biodiversity:

Biodiversity is the term which describe the combined diversity at all the fevels of biological organisation. Biodiversity and its conservation are now vital environmental issues of international concern as more and more people around the wold begin to realise the critical importance of biodiversity for our survival and well-being on this planet.

The testis which are situated outside the abdominal cavity within a pouch called scrotum. 

The scrotum helps to maintain the low temperature of testes necessary for spermatogenesis.

In vitro fertilisation (IVF-fertilisation outside the body in almost similar conditions as that in the body) followed by embryo transfer (ET) is one of such methods. In this method, popularly known as test tube baby programine, ovar from the wife/donor (female) and sperms from the husband/donor (mole) are collected and are induced to form zygote under stimulated condition in the laboratory.

An important charactrtic of all communities is that composition and structure constantly change in response to the changing environmental conditions. This change is orderly and sequential, parallel with changes in the physical environment. The gradual and faulty predictable change in the species composition of a given area is called ecological succession.

Transgenic bacteria – Bacteria that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic bacteria. 

Example – The bacteria E.coli is a transgenic bacteria used to produce insulin to cure diabetes. Insulin molecule is made up of two peptide chains : Chain A and Chain B. The two DNA sequences corresponding to A & B, chains of human insulin are prepared thorugh genetic engineering. 

Some of the sexually transmitted diseases with their causative organisms are:

Gonorrhoea - bacteria

syphilis - bacteria

Genital herpes - Virus

Genital warts - Virus

Followings are differences between spermatogenesis and oogenesis :–

Oogenesis is different from that of spermatogenesis in the following ways:

• In spermatogenesis, continuous production of sperms takes place from puberty to old age. Whereas, in oogenesis, the oocytes are generated before birth/ in the foetus.
• A large number of these oocytes degenerate during the phase from birth to puberty. The oocytes continuously decrease in number, and it gets completely exhausted at menopause. 
• A primary spermatocyte completes the first meiotic division leading to formation of two equal sized secondary spermatocytes whereas, Primary oocyte divides unequally by the first meiotic division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body.
• Meiotic division of secondary oocyte gets temporarily arrested at Prophase-I stage. It is completed only when a sperm comes in contact with the zona pellucida layer of the ovum. There is no such event in spermatogenesis.
• Spermatogonium produces 4 functional spermatozoa whereas an oogonium produces one functional ovum and 3 non-functional polar bodies.

The sequence of steps that take place in a PCR are listed as follows. 

(i) The target DNA is mixed with Taq polymerase, the two oligonucleotide primers and nucleotides. Very small amount of target DNA (just a single molecule) is sufficient as PCR is extremely sensitive. 

(ii) When the mixture is heated to a temperature >90°C, the DNA molecule denatures. The hydrogen bonds that hold together the two polynucleotides of the double helix are broken, so the target DNA becomes denatured to single stranded molecules. 

(iii) The mixture is then cooled down to 50–60 °C where the primers anneal to the DNA molecules at specific positions. The two strands of DNA can also rejoin at this temperature. 

(iv) When the temperature is again raised above 70°C, the DNA polymerase enzyme attaches to one end of each primer and synthesizes new strands of DNA, complementary to the template DNA molecules. 

(v) Now there are four strands of DNA (two original and two new). This process is called extension by which the enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. When the temperature is then increased back to >90°C, the double-stranded DNA molecules (each of which consists of one strand of the original molecule and one new strand of DNA) denature into single strands. 

(vi) The second cycle of denaturation-annealing-synthesis, at the end of which there are eight DNA strands. This means that after 30 cycles, there will be over 1 billion products derived from each starting molecule.

At the end of a PCR, a sample of the reaction mixture is usually analyzed by agarose gel electrophoresis. The DNA produced should be sufficient for the amplified fragment to be visible as a discrete band after staining with EtBr.

(a) (H)−(iii); (I)−(iv); (J)−(i); (K)−(ii) 

• Penicillium mould contaminating a culture of Staphylococcus bacteria had prevented growth of bacteria close to itself. He was the first to recognize the potential for countering infections. The bacteria could not grow because of the substance produced by the mould. Fleming named the substance as penicillin after the mould Penicillium notatum. 

• Cyclosporin A is produced by the fungus Trichoderma polysporum and Cylindrocarpon lucidum. It is used as an immunosuppressive agent that prevents rejection in patients who have had transplants of kidney, bone marrow, liver, pancreas, etc. 

• Statins are produced by the yeast Monascus purpureus. They are used as agents that lower the blood-cholesterol. 

• Ethanol (ethyl alcohol) is produced by the fermentation of substrate such as grains, fruit juice, vegetables and other ingredients. The yeasts used in brewing for preparing juices or alcoholic drinks are called brewer’s yeast. For example, yeast Saccharomyces cerevisiae is used in the fermentation of juices or cereals. 

(b) In Swiss cheese, the bacterium Propionibacterium shermanii ferments lactic acid and produces propionic acid, acetic acid and carbon dioxide. The acids provide flavor to the cheese and the carbon dioxide, which becomes trapped in the curd, produces the characteristic holes in the cheese.

(b) Spermatogenesis is initiated due to increase in gonadotropin-releasing hormone (GnRH) by hypothalamus. This hormone stimulates anterior pituitary to secrete two gonadotropins: luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH acts on the Leydig’s cells of the testes and stimulates them to synthesize and secrete androgens (testosterone) which in turn stimulate spermatogenesis. FSH acts on Sertoli cells of seminiferous tubules of the testes and stimulate them to secrete an androgen binding protein (ABP) and inhibin. ABP binds to testosterone, keeping its concentration high, thus stimulating the final steps of spermatogenesis in the seminiferous tubules. Once the degree of spermatogenesis required for male reproductive functions has been achieved, Sertoli cells release inhibin, a protein hormone named for its role in inhibiting FSH secretion by the anterior pituitary.

The primary sex organs: The testis in the males and the ovaries in the females - produce gametes i.e. sperms and ovum respectively by the process called gametogenesis.

The production of serms by the immature germ cells is called spernatogenesis where the process of formation of a mature female gamete is known as oogeneis.

Isotherman process: A process is said to be isothermal in case the temperature of the system remains fixed or constant i.e., operation is carried at constant temperature. 

Adiabatic process: In an adiabatic process, no exchange of heat between the system and the surroundings is possible i.e., the system is completely isolated or insulated from the surroundings.

(i) Stagnant water is breeding place for mosquito population. 

(ii) They feed on human blood and transmit disease from infected person to healthy person. So, Bhanu is correct.

2Fe + 2HCl → FeCl₂ + H₂ 

Fe → Fe²⁺ + 2e^- 

2H⁺ + 2e^- → H₂

Oxidation number is the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that the electrons in a covalent bond belong entirely to the more electronegative elements. 

Oxidation number of Cl in KClO₃ is +5.